Delivery systems for expandable and other implantable medical devices such as stents, grafts, stent-grafts and vena cava filters are a highly developed and well known field of medical technology. Implants such as stents have many well known uses and applications. A stent is a prosthesis which is generally tubular and which is expanded radially in a vessel or lumen to maintain the patency of the vessel or lumen. Stents are widely used in body vessels, body canals, ducts or other body lumens.
The delivery systems for stents and similar medical devices are generally comprised of catheters with the medical device axially surrounding the distal end of the catheter. It is highly desirable to keep the profile of the catheter as small as possible in order to more readily pass through tortuous vessels. To that end, self-expanding and balloon expandable medical devices are ideally confined in a reduced radius for delivery to the deployment site. Once the medical device is deployed, the catheter is removed leaving the medical device implanted at the desired location in order to keep the vessel walls from closing.
Typically, separate catheters have been used to dilate a vessel and to deliver a medical device such as a stent. This requires one or more catheter exchanges during the procedure, which increases the time and cost for delivering the medical device. Some delivery systems have attempted to overcome these problems with limited success.
U.S. Pat. No. 5,632,760 to Sheiban et al (Sheiban) attempts to circumvent the problem of multiple catheter exchanges by including two balloons in a single catheter. The first balloon dilates the vessel and the second balloon expands the stent. While the Sheiban catheter allows the user to avoid multiple catheter exchanges, it presents a large profile in the region of the stent.
U.S. Pat. No. 5,810,871 to Tuckey et al (Tuckey) uses a balloon that longitudinally and slidingly runs through an expandable sheath with a stent mounted over the sheath. Such a configuration however has a relatively large profile as a consequence of xe2x80x98stackingxe2x80x99 the balloon, sheath, and stent upon one another.
There remains a need for reduced profile medical device delivery systems which use a single balloon.
For the purposes of this disclosure, the term medical prosthesis shall refer to stents, grafts, stent-grafts, vena cava filters and other expandable endoluminal prostheses.
All U.S. patents and patent applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
The invention in various of its embodiment is summarized below. Additional details of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
In one embodiment, the invention is directed to a medical device delivery catheter comprising a slidable balloon which is initially displaced from the stent or other expandable medical device. The balloon may be moved underneath the stent to expand the stent or to seat an already expanded stent. Because the balloon is displaced from the stent, the medical device delivery catheter has a low-profile thereby allowing the catheter to be more easily manipulated and positioned within a vessel than prior higher profile catheters.
More particularly, in one embodiment, the invention is directed to a medical device delivery catheter comprising an inner tube having a medical device receiving region at the distal end and a balloon assembly movably disposed about the inner tube. The balloon assembly comprises a medical balloon displaced from the medical device receiving region. Additionally, the balloon assembly may comprise one or more sliding seals. A retractable outer sheath is disposed about the inner tube and is movable relative to the inner tube to expose the medical device receiving region. The catheter further comprises a balloon assembly engagement member capable of movably engaging the outer sheath to the balloon assembly on moving the outer sheath in a predetermined direction. The catheter further comprises an inflation lumen capable of fluid communication with the medical balloon and which supplies inflation fluid to the balloon. Finally, the catheter comprises an expandable medical device such as those disclosed above disposed about a distal portion of the inner tube, distal to the medical balloon.
In another embodiment of the invention, the catheter is constructed and arranged such that once the balloon assembly and outer sheath are engaged, distal movement of the outer sheath moves the balloon assembly in a distal direction. Proximal movement of the outer sheath results in little or no movement of the balloon.
The invention contemplates several types of unidirectional balloon assembly engagement members including a strip of oriented fibers and a hook. In one embodiment of the invention, the retractable outer sheath may be used to engage and move the balloon. In another embodiment of the invention, a push member is used to engage and move the balloon.
The invention is also directed to a method of delivering a medical device to a desired bodily location. In accordance with the method, a medical device delivery catheter is provided. The catheter has an inner tube having a medical device receiving region at the distal end and a balloon moveably disposed about the inner tube. The balloon is displaced from the medical device receiving region. The catheter further comprises a balloon moving device operably connected to the balloon and a medical device disposed about the medical device receiving region. The medical device delivery catheter is inserted into a body vessel and advanced through the vessel to a determined bodily location. The balloon is moved relative to the inner tube such that at least a portion of the balloon lies between the medical device and the inner tube and inflated thereby thereby engaging the medical device and positioning the medical device in a desired bodily location. Following positioning of the medical device, the balloon is deflated and the medical device delivery catheter withdrawn from the vessel.
Additional details and/or embodiments of the invention are discussed below.